Centrifugal compressor or blower



CENTRIFUGAL COMPRESSOR 0R BLOWER Filed April 12, 1926 Ill/11110111.

J v% 14' Fig.3. 4% y v I g} I I Patented Sept. 21,1926.

UNITED its.

ADOLF BAUMANN, OF BADEN, SWITZERLAND, ASSIGNOB TO AKTIENGESELLSCHAFT BROWN. BOVERI & CIE., OF BADEN, SWITZERLAND, A JOINT STOCK COMPANY.

CENTRIFUGAL COMPRESSOR OR BLOWER.

Application filed April 12, 1926, Serial No. 101,417, and in Germany A m-i123, 1925.

peripheral speeds without'necessitating "a.

proportionate increase in the weight and size of th'e'impeller wheels. I Another object is the provis on of a construction which will afford increase of strength in the impeller wheels without neout or indicated hereinafter or obviousrto one skilled in the art upon an understandingv ofthe invention: f In the drawing forming a part of this S ecificati nare illustrated certain constructions whe eby the invention may be availed of, but, it is to be understood that the. various embodiments of the invention may differ in detail from; the construction here shown .for purpose of illustration.

In the drawing, Fig. 1 is a marginal view or side elevation of an impeller blade.

Fig. 2 1S a'perspective-view of one form of blade section. I

Fig. 3 is a transverse sectional view of another form of blade section.

Fig. 4 is a diagrammatic illustration of'a group. of impeller wheels, same shown in part diametrical section.

I Fig. 5 is another group of such wheels illustrated in similar fashion, and

Fig. '6} is a similar illustration of a third group of wheels.

Limitations are imposed on the peripheral speed at which centrifugal blowers or'compressors may be operated and upon the eflfectiveoutput, by the weight of the impeller ,wheels. When operated at high peri heral speeds, the blades must be of very su stantial strength, but substantial increase in the weight of metal in the blades in turn increases the stresses to which the shroud discs and hubs are subjected, thus necessitatin a commensurate increase in the weight of those parts. As the weight of the impeller wheels is increased, however, the number'that may be mounted on a single shaft is reduced, owing to consideration of critical s eed. Various types of light metal of ligh tensile strength, such as duraluminium are available, but heretofore the use of such metals for the blading has presented difficulties making it impracticable due to the differences in the thermal'expansion coefficients between such metals and the steel discs which upport the blading.

The present invention makes possible the use of such metals in the blading, with the resulting advantages in the direction of increased strength for weight and size inboth blades and discs, the increase of'operating speeds and output, together with various other advantages inithe direction of economy of production. The nature'of the invention will be understood by reference to the drawing in which Fig. 1 shows amarginal view or side elevation of an impeller blade, the samebeing made up of a plurality of small sections 10, one form of section being shown in detail in Fig. 2, and appro, priately shaped end sections 11.- These sections may be formed of a suitable light metal of high tensile strength such as dura-' luminium, by die-casting or otherwise, the so sections being provided, if desired, with the integrally formed attaching rivets 12 on their margins. For purpose of weight reduction they may be formed with interior cored spaces 14. The sections are assembled between the shroud discs .15 and 16 and secured thereto by meansof the rivets 12, the-several sections being disposed in proper relationship to constitute a blade of the desired'form.

The several sections forming a blade are not placed in close abutment, but small spaces 17 are left between the adjacent edges. These constitute expansion spaces aceomodating the expansion of the portions of the sections beyond the rivets, thus relieving both the discs and the blades of the effects of a cumulative expansion of metal throughout the length of the blade. Not only does this relieve the rivets of theshearing action which would 'result from the difi'erence in expansion of the steel discs and alloy blades, but also contributes to the strength and stability of the connection of the two discs 2 l mama By suitable selection of sizes for'the blade sections, uniform standardized sizes may be employed in the construction of impeller wheels of different diameters. For example,

Fig. 4 shows a series of impeller wheels graded into'difierent sizes so as to operate in accordance with a definite law governing the design of such elements, the diflerent sizes varying both in diameter of the wheel and in width of the blades.

Fig. 5 shows another group in which' the diameters correspond respectively to the diameters of the forms B, C and D of Fig. 4, but the blades in each are narrower than those in the wheels of corresponding diameter in the other-group. V In Fig. 6 areshown sections of two other Wheels, that designated H corresponding in diameter to wheels F and C, and that designated I corresponding in diameter to G and D, but in each instance the blades are of less Width. However, the width of the blades in the forms H, E and A are the same, and

the sections of,which the blades are formed are the same size. The same holds true for the forms I, F and B and for the forms Grand C. This demonstrates how Wheels of different sizes may be builtup using blade sections ofuniforrn design and size.

A. further advantage accrues from the constructionof the blades in this fashion by virtue of the facility by which advantageous details of construction may be incorporated for example, in Fig. 3 is shown a blade section in which the member is given a form constituting a beam of uniform strength throughout its width. What I clam is 1. Construction for rotary compressors comprising shroud discs and interposed impeller blades, the respective blades being formed of a plurality of sections of a light metal different from that of the discs, with expansion spaces between sections.

sections arranged with intervening expan-.

sion spaces.

4. In an impeller wheel, an impeller blade comprising a plurality ofsections arranged with intervening expansion spaces, the sections having marginal securing members.

5. An impellerwheel comprising shroud discs and intervening impeller blades, the blades comprising a lurality of identical sections of ii ht meta l difi'erent from that of the discs, t e sections constituting a blade being arranged with intervening expansion spaces.

6. A blade construction for impeller wheels comprising identical blade sections formed of light metal and having marginal mounting members, said sections having smooth external faces and internal cavities for hghtening efiect.

In testimony whereof I have hereunto subscribed my name at Zurich,-Switserland, on the 26 day of March A. D. 1926. I

ADGLF BAUMANN. 

